Hydraulic Retention Time (HRT)
Calculate the hydraulic retention time (HRT) of a reactor or tank, HRT = volume ÷ flow, dividing the working volume (m³) by the influent flow (m³/h). The result, in hours, is the average time the liquid stays in the unit and is decisive in designing clarifiers, anaerobic reactors, lagoons and aeration tanks: short times prevent reactions or settling from completing, while long times raise cost and footprint. Enter the working volume and the inlet flow.
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Tempo de detenção hidráulica (TDH)
O tempo de detenção hidráulica (TDH, ou HRT) é o tempo médio que uma porção de líquido permanece dentro de um reator ou tanque, e sai direto da definição de vazão: TDH = volume ÷ vazão. Se um tanque de 200 m³ recebe 50 m³ por hora, em média cada gota fica 4 horas lá dentro. É um parâmetro central de qualquer unidade de tratamento porque os processos — sedimentação de partículas, digestão anaeróbia, oxidação biológica, contato com desinfetante — precisam de tempo para acontecer. TDH curto demais não deixa a reação ou a decantação se completarem (eficiência cai); TDH longo demais exige tanques enormes, encarecendo a obra e ocupando área. Por isso cada processo tem sua faixa típica: decantadores trabalham com horas, reatores anaeróbios e lagoas com horas a dias. Atenção: o TDH é o tempo teórico ideal — curtos-circuitos hidráulicos e zonas mortas fazem o tempo real ser menor que o calculado. Informe o volume útil e a vazão de entrada.
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Spillway Discharge (Creager/Ogee)
Calculate the discharge over a Creager/ogee dam spillway, Q = C·L·H^1.5, from the discharge coefficient C (typically 2.0-2.2 in SI for well-designed ogee profiles), the crest length L (m) and the head over the crest H (m). The spillway is a dam's most critical safety structure: it releases floods safely, preventing overtopping — the leading cause of dam failure. The ogee profile follows the shape of the underside of a free nappe, maximizing discharge while keeping crest pressure near atmospheric (avoiding cavitation). The coefficient C absorbs gravity and approach effects, exceeding that of a sharp-crested weir. Spillway design starts from the design flood (often the 10,000-year flood or the PMF) and sets the required crest length. Enter the discharge coefficient, crest length and head.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.